The project is concerned with identification of the peripheral lymphoid cells with cytolytic activity towards autologous and allogeneic target cells of urothelial origin. Patient with transitional cell carcinoma of bladder (TCC) with localized disease have been shown to have effector cells capable of exerting elevated lysis of the allogeneic cell line T24 (derived from TCC). TCC patients with progressive disease do not exhibit this reactivity. A patient with chronic cystitis with heavy plasma cell infiltrates into the bladder mucosa has been identified who also has effector cells in the blood with selective cytolytic activity toward certain TCC cells in culture. This work is now being extended to search for cytolytic activity toward autologous urothelial cells in patients with TCC and cystitis. The effector cells will be characterized according to conventional surface markers into T, B or null cell subsets.